Re: [Hat] Oddness...

On 18 Jul 2005, at 16:58, Malcolm Wallace wrote:

Thomas Davie writes:

...

I've been trying to get hat-trans to eat QuickCheck, without much success. Is there something I'm missing? I'm getting this error:

hat-trans QuickCheck.hs hat-trans: Variable or constructor not in scope: chr

The QuickCheck.hs module available from John Hughes' webpage was written for an older version of Hugs which wasn't compliant with Haskell'98. The 'chr' function is exported from the standard Char library.

However, I have to wonder whether it makes any sense to trace QuickCheck itself? In the AFP summer school 2002, the students used QC to find a failure, then fed only that failing case into Hat to discover its cause.

For delta-debugging, I expect you would want both a failing case and a passing case, but I don't suppose you really want to bother with tracing all the QC machinery that found them for you.

True, this was really an attempt at a first hack that involved running quickcheck (and thus getting multiple successes and failures that are easy to identify)... Look for evaluations of function starting prop_ and use them to do some delta debugging... Before I start accepting multiple traces, etc. Bob